Lighting circuit 1.5mm and 1.00mm drop

[jase31]

Is there anything in the regs against using 1.5m for a lighting radial, and 1.0m for switchdrops. Using 1mm makes switch cable identification easier.

 

[malcolmsanford]

no as long as the 1mm satisfies the Iz of the circuit

 

[telectrix]

ditto^^^^^^ the 3core used for 2way switching is generally 1.0mm. another way of ID'ing the switch drops is to use twin red. apart from the obvious solution of MARKING THE CABLES.

TIN HAT ON WAITING FOR SOMEONE TO SCREAM BROWN

 

[Tuttle]

It does mean though that you shouldn't put the cables into the same terminals as they are different sizes. Not a problem for ceiling roses, but if you end up removing a ceiling rose and fitting a junction box in the ceiling instead the then have to be careful what sort of junction box you use, which can be a bit of a pain.

 

[malcolmsanford]

Could you expand on that Tuttle?

 

[Tuttle]

In a ceiling rose, all the cores go to separate screw terminals so it doesn't matter that some are 1.5mm and some are 1.0mm. If you remove the ceiling rose to fit a light fitting that doesn't have the 3 plate connection inside, and try to use one of the old fashion style round junction boxes with 4 terminals in instead, you find that you need to put a 1.5mm and a 1.0mm core into the same terminal, which I think is not allowed.

 

[malcolmsanford]

Who is it not allowed by?

 

[trev]

Bad practice Tuttle but I don't think it's expressly prohibited mate

 

[Sparky_Ben]

surely in the ceiling rose they go into the same block anyway, although are just held in place by seperate screws, in my eyes still the same terminal overall?

 

[telectrix]

think his point is that if you put a 1.5 mm and a 1.0mm under the same screw, the 1.0mm will not be secure

 

[Tuttle]

Bad practice Tuttle but I don't think it's expressly prohibited mate

I was told not to do it, I've seen it written in books, I assumed that I'd also seen it in the regs somewhere, but I can't find it now so I think you're probably right - just bad practice.

 

[malcolmsanford]

Have a read of sections 526 and then reg 522.8 which are the regs concerning connections

 

[Tuttle]

Have a read of sections 526 and then reg 522.8 which are the regs concerning connections

I've already looked at 526, and I can't see any mention in 522.8 either.

I am a bit surprised though given the number of times I was told not to do it!

 

[malcolmsanford]

As Trev said mate it is another one of these myths that have grown up over the years.